In the software, you may of noticed that the Robo 3D profile has two profiles, one for Robo 3D's with auto-levelers and one for Robo 3D's that don't have autoleveling capabilities.
To have auto-leveling, you need extra end-stops that can detect when your nozzle touches the bed of your printer and these settings need to be configured in your firmware. There are many Solidoodle printers, Robo printers, RepRap designs, all of whom support this Marlin feature.
Nuts n Bolts- How it works
The extruder will move to 9 different points on the bed, and probe each of them. It knows the X-Y location of where it's probing, and it can measure how far off the Z-plane is. Here you can see that the Z-plane measurements range from -.45 to -1.75 mm, a full 1.3 mm off (or 6 layers of standard printing). After probing these 9 spots, it will know the beds plane (since the bed is not flat) and will compensate when printing by moving in the Z-axis as printing.
For standard prints, the Z-axis will move only when changing layers, however if the bed-leveling feature is enabled, then the Z axis will constantly be moving to adjust and compensate.
For more information, a great read from the Robo 3D forums: http://forums.robo3dprinter.com/index.p ... elly.2574/
How to use it:
The command that runs the Auto-leveling is G29 *Marlin Firmware's with bed leveling enabled*. However, you may also find that M565 Z-1 helps set an offset for the auto-leveler. This command is optional, many people find they get better performance with it, however there's also many Robo owners who use M565 Z0 (which effectively means it's not there) and get great first layers as well.
G28 ; home all axes
G1 Z5 F5000 ; lift Z by 5mm
M565 Z-1 ; set the offset for auto-leveling mechanism
G29 ; run auto-level
Conclusion:
G29 is an amazing command and uses the mathematics of probing the 9 points to make 3D printing easier. However, if you can manually adjust your print bed, to help create a level plane that is also great, since you don't want to be overly dependent on the G29 command.
